import 'package:flutter/material.dart';
import 'package:media_kit_video/media_kit_video.dart';

import '../../../core/player/feed_player_pool.dart';

/// Feed 用的抖音风格视频播放器：
/// - 覆盖 Video(controller: pool.controllerAt(slot))
/// - 底部一条 2px 细线进度条（已播白 / 未播半透明白）
/// - 按住拖动变厚 + 出现 thumb，松手 seek 后恢复
class VideoPlayerView extends StatefulWidget {
  const VideoPlayerView({
    super.key,
    required this.pool,
    required this.slotIndex,
    required this.coverUrl,
    required this.isCurrent,
  });

  final FeedPlayerPool pool;
  final int slotIndex;
  final String coverUrl;

  /// 该页是否为当前页（暂停图标只在当前页显示，避免划走后旧页残留大图标）
  final bool isCurrent;

  @override
  State<VideoPlayerView> createState() => _VideoPlayerViewState();
}

class _VideoPlayerViewState extends State<VideoPlayerView> {
  late final PlayerSlot _slot = widget.pool.slotAt(widget.slotIndex);
  Duration _position = Duration.zero;
  Duration _duration = Duration.zero;
  bool _seeking = false;
  double _seekValue = 0;   // 拖动中的视觉值（0~1），拖动期间直接控制 painter

  @override
  void initState() {
    super.initState();
    _slot.player.stream.position.listen((p) {
      if (mounted && !_seeking) setState(() => _position = p);
    });
    _slot.player.stream.duration.listen((d) {
      if (mounted) setState(() => _duration = d);
    });
  }

  double get _value {
    if (_seeking) return _seekValue;
    final total = _duration.inMilliseconds;
    if (total <= 0) return 0;
    final cur = _position.inMilliseconds.clamp(0, total);
    return cur / total;
  }

  void _onSeekStart(double v) {
    setState(() {
      _seeking = true;
      _seekValue = v;
    });
  }

  void _onSeek(double v) {
    setState(() => _seekValue = v);
  }

  void _onSeekEnd(double v) {
    setState(() => _seeking = false);
    final totalMs = _duration.inMilliseconds;
    if (totalMs > 0) {
      _slot.player.seek(Duration(milliseconds: (v * totalMs).round()));
    }
  }

  @override
  Widget build(BuildContext context) {
    return Stack(
      fit: StackFit.expand,
      children: [
        // 底层：纯画面（media_kit 官方 Video，无控制条）
        Video(
          controller: _slot.controller,
          controls: NoVideoControls,
          fit: BoxFit.contain,
        ),

        // 封面兜底：position==0 时显示（仅未渲染第一帧）
        StreamBuilder<Duration>(
          stream: _slot.player.stream.position,
          initialData: _slot.player.state.position,
          builder: (_, snapshot) {
            final pos = snapshot.data ?? Duration.zero;
            final showCover =
                widget.coverUrl.isNotEmpty && pos == Duration.zero;
            return showCover
                ? Image.network(
                    widget.coverUrl, fit: BoxFit.cover,
                    errorBuilder: (_, __, ___) => const SizedBox.shrink(),
                  )
                : const SizedBox.shrink();
          },
        ),

        // 暂停态大播放图标：只在当前页、且该槽位确实处于暂停态时显示
        if (widget.isCurrent)
          IgnorePointer(
            child: StreamBuilder<bool>(
              stream: _slot.player.stream.playing,
              initialData: _slot.player.state.playing,
              builder: (_, snapshot) {
                final playing = snapshot.data ?? false;
                if (playing) return const SizedBox.shrink();
                return const Center(
                  child: Icon(
                    Icons.play_arrow_rounded,
                    size: 88, color: Colors.white70,
                  ),
                );
              },
            ),
          ),

        // 抖音风格细进度条（贴底，常驻）
        Positioned(
          left: 0, right: 0, bottom: 0,
          child: _ThinProgressBar(
            value: _value,
            onChanged: _onSeek,
            onChangeStart: _onSeekStart,
            onChangeEnd: _onSeekEnd,
          ),
        ),
      ],
    );
  }
}

class _ThinProgressBar extends StatefulWidget {
  const _ThinProgressBar({
    required this.value,
    required this.onChanged,
    required this.onChangeStart,
    required this.onChangeEnd,
  });
  final double value;
  final ValueChanged<double> onChanged;
  final ValueChanged<double> onChangeStart;
  final ValueChanged<double> onChangeEnd;

  @override
  State<_ThinProgressBar> createState() => _ThinProgressBarState();
}

class _ThinProgressBarState extends State<_ThinProgressBar> {
  bool _dragging = false;
  double _dragValue = 0;

  void _update(Offset local, double width) {
    final v = (local.dx / width).clamp(0.0, 1.0);
    _dragValue = v;
    widget.onChanged(v);
  }

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (_, constraints) {
        final w = constraints.maxWidth;
        return GestureDetector(
          behavior: HitTestBehavior.opaque,
          onHorizontalDragStart: (d) {
            setState(() => _dragging = true);
            widget.onChangeStart(widget.value);
            _update(d.localPosition, w);
          },
          onHorizontalDragUpdate: (d) => _update(d.localPosition, w),
          onHorizontalDragEnd: (_) {
            setState(() => _dragging = false);
            widget.onChangeEnd(_dragValue.clamp(0.0, 1.0));
          },
          onTapDown: (d) {
            setState(() => _dragging = true);
            widget.onChangeStart(widget.value);
            _update(d.localPosition, w);
          },
          onTapUp: (_) {
            setState(() => _dragging = false);
            widget.onChangeEnd(_dragValue.clamp(0.0, 1.0));
          },
          child: Container(
            height: 32, // 触摸热区 32px（视觉 2px，好点）
            alignment: Alignment.bottomCenter,
            child: CustomPaint(
              painter: _ProgressPainter(
                value: _dragging ? _dragValue : widget.value,
                dragging: _dragging,
              ),
              size: Size(w, _dragging ? 20 : 4),
            ),
          ),
        );
      },
    );
  }
}

class _ProgressPainter extends CustomPainter {
  _ProgressPainter({required this.value, required this.dragging});
  final double value;
  final bool dragging;

  @override
  void paint(Canvas canvas, Size size) {
    final h = dragging ? 3.0 : 2.0;
    final y = size.height / 2;

    final track = Paint()
      ..color = Colors.white.withValues(alpha: dragging ? 0.35 : 0.22)
      ..strokeCap = StrokeCap.round
      ..strokeWidth = h;
    canvas.drawLine(Offset(0, y), Offset(size.width, y), track);

    if (value > 0) {
      final played = Paint()
        ..color = Colors.white
        ..strokeCap = StrokeCap.round
        ..strokeWidth = h;
      canvas.drawLine(Offset(0, y), Offset(value * size.width, y), played);
    }

    if (dragging) {
      canvas.drawCircle(
        Offset(value * size.width, y), 6,
        Paint()..color = Colors.white..style = PaintingStyle.fill,
      );
    }
  }

  @override
  bool shouldRepaint(covariant _ProgressPainter old) =>
      value != old.value || dragging != old.dragging;
}